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Exclusive breastfeeding to reduce the risk of childhood overweight and obesity

Biological, behavioural and contextual rationale

WHO technical staffSeptember 2014

The positive impact of breastfeeding on lowering the risk of death from infectious diseases in the first two years of life is now well-established (1). A mounting body of evidence suggests that breastfeeding may also play a role in programming noncommunicable disease risk later in life (2-13) including protection against overweight and obesity in childhood (2-6).

While the precise pathways underlying the potential protective effect of breastfeeding on overweight and obesity remain unknown, several plausible mechanisms have been proposed. Exclusive breastfeeding precludes inappropriate complementary feeding practices such as early introduction of complementary foods that could lead to unhealthy weight gain. Protein and total energy intake, as well as the amount of energy metabolised, are higher among formula-fed infants relative to breastfed (14,15), leading to increased body weight during the neonatal period (10) and data suggests that both higher protein intake (16) and weight gain (17) early in life is positively associated with the development of obesity later in childhood. Differences in release of insulin and other pancreatic and gut hormones have also been observed between breastfed and formula-fed infants, with formula feeding leading to higher plasma levels of insulin which in turn would stimulate fat deposition and early development of adipocytes, the cells that store fat (18). Breast milk itself contains hormones and other biological factors involved in the regulation of food intake and energy balance which may help shape long-term physiological processes responsible for maintaining energy balance (19). By moderating the impact of physiological processes that promote weight gain during infancy, breastfeeding might assist in “programming” an individual to be at reduced risk for overweight and obesity later in life (20).

Despite the numerous benefits of breastfeeding, breastfeeding rates remain low in many parts of the world. Actions to increase the rate of breastfeeding include:

education and support of mothers throughout pregnancy and beyond;

support and protection of breastfeeding in the workplace;

implementation of the Baby-Friendly Hospital Initiative; and

implementation of and adherence to the International Code of Marketing of Breast-milk Substitutes.

Most of the studies on the long-term consequences of breastfeeding have been carried out in high-income countries. The limited number of studies conducted in low- and middle-income countries thus far have generally not shown the same protective effect of breastfeeding observed in high-income country settings (21-22), though the participants in the low- and middle-income country studies were not exclusively children (age range 15-41 years of age) (22), which may help to explain the lack of protective effective observed (e.g. the effect might be less pronounced in adults which would attenuate the overall effect). Additionally, differences in breastfeeding rates, available alternatives to breast milk (e.g. commercially manufactured, derived from animal sources), socioeconomic structure and other environmental and cultural factors may also explain some of the conflicting observations (21).

While it is considered unethical to randomly allocate subjects not to receive breast milk, well-conducted randomized controlled trials comparing intensive or comprehensive education to standard hospital care on long-term health outcomes may help to control for many of the confounding factors described above and thus further clarify the association between breastfeeding and long-term health outcomes. Very few such studies have been conducted to date; an intent to treat analysis of data from a large trial conducted in Belarus, comparing hospitals incorporating feeding practices and policies modelled on the Baby-friendly Hospital Initiative (23) to those following standard feeding practices, demonstrated a significant association only between breastfeeding and IQ in children (24). In addition, most studies included in meta-analyses have made different comparisons in terms of exclusively breastfed, ever breastfed and mixed feeding to never breastfed as well as differences in duration of breastfeeding. Further research is needed that assesses the impact of exclusive breastfeeding for longer periods of time and which takes into consideration various contextual factors, particularly in low- and middle-income countries, some of which are experiencing rapidly increasing rates of obesity (25).

Based on the available evidence, breastfeeding appears to provide some level of protection against childhood overweight and obesity. Together with other targeted nutrition interventions, breastfeeding can therefore be an important component of strategies to reduce the risk of overweight and obesity in children.

References

1. WHO. Effect of breastfeeding on infant and child mortality due to infectious diseases in less developed countries: a pooled analysis. WHO Collaborative Study Team on the Role of Breastfeeding on the Prevention of Infant Mortality. The Lancet. 2000; 355(9202):451-5.

14. Heinig MJ, Nommsen LA, Peerson JM, Lonnerdal B, Dewey KG. Energy and protein intakes of breast-fed and formula-fed infants during the first year of life and their association with growth velocity: the DARLING Study. American Journal of Clinical Nutrition. 1993; 58(2):152-161.

15. Whitehead RG. For how long is exclusive breast-feeding adequate to satisfy the dietary energy needs of the average young baby? Pediatric Research. 1995; 37(2):239–43.

16. Rolland-Cachera MF, Deheeger M, Akrout M, Bellisle F. Influence of macronutrients on adiposity development: a follow up study of nutrition and growth from 10 months to 8 years of age. International Journal of Obesity and Related Metabolic Disorders. 1995; 19(8):573-8.